#ifndef GRAPH_H

#define GRAPH_H

#include "diff.h"

/**

 * The graph API is used to draw a text-based representation of the commit

 * history. The API generates the graph in a line-by-line fashion.

 *

 * Calling sequence

 * ----------------

 *

 * - Create a `struct git_graph` by calling `graph_init()`.  When using the

 *   revision walking API, this is done automatically by `setup_revisions()` if

 *   the '--graph' option is supplied.

 *

 * - Use the revision walking API to walk through a group of contiguous commits.

 *   The `get_revision()` function automatically calls `graph_update()` each time

 *   it is invoked.

 *

 * - For each commit, call `graph_next_line()` repeatedly, until

 *   `graph_is_commit_finished()` returns non-zero.  Each call to

 *   `graph_next_line()` will output a single line of the graph.  The resulting

 *   lines will not contain any newlines.  `graph_next_line()` returns 1 if the

 *   resulting line contains the current commit, or 0 if this is merely a line

 *   needed to adjust the graph before or after the current commit.  This return

 *   value can be used to determine where to print the commit summary information

 *   alongside the graph output.

 *

 * Limitations

 * -----------

 * - Check the graph_update() function for its limitations.

 *

 * - The graph API does not currently support reverse commit ordering.  In

 *   order to implement reverse ordering, the graphing API needs an

 *   (efficient) mechanism to find the children of a commit.

 *

 * Sample usage

 * ------------

 *

 * ------------

 * struct commit *commit;

 * struct git_graph *graph = graph_init(opts);

 *

 * while ((commit = get_revision(opts)) != NULL) {

 * 	while (!graph_is_commit_finished(graph))

 * 	{

 * 		struct strbuf sb;

 * 		int is_commit_line;

 *

 * 		strbuf_init(&sb, 0);

 * 		is_commit_line = graph_next_line(graph, &sb);

 * 		fputs(sb.buf, stdout);

 *

 * 		if (is_commit_line)

 * 			log_tree_commit(opts, commit);

 * 		else

 * 			putchar(opts->diffopt.line_termination);

 * 	}

 * }

 * ------------

 * Sample output

 * -------------

 *

 * The following is an example of the output from the graph API.  This output does

 * not include any commit summary information--callers are responsible for

 * outputting that information, if desired.

 * ------------

 * *

 * *

 * *

 * |\

 * * |

 * | | *

 * | \ \

 * |  \ \

 * *-. \ \

 * |\ \ \ \

 * | | * | |

 * | | | | | *

 * | | | | | *

 * | | | | | *

 * | | | | | |\

 * | | | | | | *

 * | * | | | | |

 * | | | | | *  \

 * | | | | | |\  |

 * | | | | * | | |

 * | | | | * | | |

 * * | | | | | | |

 * | |/ / / / / /

 * |/| / / / / /

 * * | | | | | |

 * |/ / / / / /

 * * | | | | |

 * | | | | | *

 * | | | | |/

 * | | | | *

 * ------------

 *

 */

/* A graph is a pointer to this opaque structure */

struct git_graph;

/*

 * Called to setup global display of line_prefix diff option.

 *

 * Passed a diff_options structure which indicates the line_prefix and the

 * file to output the prefix to. This is sort of a hack used so that the

 * line_prefix will be honored by all flows which also honor "--graph"

 * regardless of whether a graph has actually been setup. The normal graph

 * flow will honor the exact diff_options passed, but a NULL graph will cause

 * display of a line_prefix to stdout.

 */

void graph_setup_line_prefix(struct diff_options *diffopt);

/*

 * Set up a custom scheme for column colors.

 *

 * The default column color scheme inserts ANSI color escapes to colorize

 * the graph. The various color escapes are stored in an array of strings

 * where each entry corresponds to a color, except for the last entry,

 * which denotes the escape for resetting the color back to the default.

 * When generating the graph, strings from this array are inserted before

 * and after the various column characters.

 *

 * This function allows you to enable a custom array of color escapes.

 * The 'colors_max' argument is the index of the last "reset" entry.

 *

 * This functions must be called BEFORE graph_init() is called.

 *

 * NOTE: This function isn't used in Git outside graph.c but it is used

 * by CGit (http://git.zx2c4.com/cgit/) to use HTML for colors.

 */

void graph_set_column_colors(const char **colors, unsigned short colors_max);

/*

 * Create a new struct git_graph.

 */

struct git_graph *graph_init(struct rev_info *opt);

/*

 * Update a git_graph with a new commit.

 * This will cause the graph to begin outputting lines for the new commit

 * the next time graph_next_line() is called.

 *

 * If graph_update() is called before graph_is_commit_finished() returns 1,

 * the next call to graph_next_line() will output an ellipsis ("...")

 * to indicate that a portion of the graph is missing.

 *

 * Limitations:

 * -----------

 *

 * - `graph_update()` must be called with commits in topological order.  It should

 *   not be called on a commit if it has already been invoked with an ancestor of

 *   that commit, or the graph output will be incorrect.

 *

 * - `graph_update()` must be called on a contiguous group of commits.  If

 *   `graph_update()` is called on a particular commit, it should later be called

 *   on all parents of that commit.  Parents must not be skipped, or the graph

 *   output will appear incorrect.

 *

 * - `graph_update()` may be used on a pruned set of commits only if the parent list

 *   has been rewritten so as to include only ancestors from the pruned set.

 */

void graph_update(struct git_graph *graph, struct commit *commit);

/*

 * Determine if a graph has finished outputting lines for the current

 * commit.

 *

 * Returns 1 if graph_next_line() needs to be called again before

 * graph_update() should be called.  Returns 0 if no more lines are needed

 * for this commit.  If 0 is returned, graph_next_line() may still be

 * called without calling graph_update(), and it will merely output

 * appropriate "vertical padding" in the graph.

 *

 * If `graph_update()` is called before all lines for the current commit have

 * been printed, the next call to `graph_next_line()` will output an ellipsis,

 * to indicate that a portion of the graph was omitted.

 */

int graph_is_commit_finished(struct git_graph const *graph);

/*

 * Output the next line for a graph.

 * This formats the next graph line into the specified strbuf.  It is not

 * terminated with a newline.

 *

 * Returns 1 if the line includes the current commit, and 0 otherwise.

 * graph_next_line() will return 1 exactly once for each time

 * graph_update() is called.

 *

 * NOTE: This function isn't used in Git outside graph.c but it is used

 * by CGit (http://git.zx2c4.com/cgit/) to wrap HTML around graph lines.

 */

int graph_next_line(struct git_graph *graph, struct strbuf *sb);

/*

 * Return current width of the graph in on-screen characters.

 */

int graph_width(struct git_graph *graph);

/*

 * graph_show_*: helper functions for printing to stdout

 */

/*

 * If the graph is non-NULL, print the history graph to stdout,

 * up to and including the line containing this commit.

 * Does not print a terminating newline on the last line.

 */

void graph_show_commit(struct git_graph *graph);

/*

 * If the graph is non-NULL, print one line of the history graph to stdout.

 * Does not print a terminating newline on the last line.

 */

void graph_show_oneline(struct git_graph *graph);

/*

 * If the graph is non-NULL, print one line of vertical graph padding to

 * stdout.  Does not print a terminating newline on the last line.

 */

void graph_show_padding(struct git_graph *graph);

/*

 * If the graph is non-NULL, print the rest of the history graph for this

 * commit to stdout.  Does not print a terminating newline on the last line.

 * Returns 1 if output was printed, and 0 if no output was necessary.

 */

int graph_show_remainder(struct git_graph *graph);

/*

 * Print a commit message strbuf and the remainder of the graph to stdout.

 *

 * This is similar to graph_show_strbuf(), but it always prints the

 * remainder of the graph.

 *

 * It is better than directly calling `graph_show_strbuf()` followed by

 * `graph_show_remainder()` since it properly handles buffers that do not end in

 * a terminating newline.

 *

 * If the strbuf ends with a newline, the output printed by

 * graph_show_commit_msg() will end with a newline.  If the strbuf is

 * missing a terminating newline (including if it is empty), the output

 * printed by graph_show_commit_msg() will also be missing a terminating

 * newline.

 *

 * Note that unlike some other graph display functions, you must pass the file

 * handle directly. It is assumed that this is the same file handle as the

 * file specified by the graph diff options. This is necessary so that

 * graph_show_commit_msg can be called even with a NULL graph.

 */

void graph_show_commit_msg(struct git_graph *graph,

			   FILE *file,

			   struct strbuf const *sb);

#endif /* GRAPH_H */