use super::editor::TextEditor;
use eframe::egui;

impl TextEditor {
    pub fn update_find_matches(&mut self) {
        let previous_match_index = self.current_match_index;
        self.find_matches.clear();
        self.current_match_index = None;

        if self.find_query.is_empty() {
            return;
        }

        if let Some(tab) = self.get_active_tab() {
            let content = &tab.content;
            let query = if self.case_sensitive_search {
                self.find_query.clone()
            } else {
                self.find_query.to_lowercase()
            };

            let search_content = if self.case_sensitive_search {
                content.clone()
            } else {
                content.to_lowercase()
            };

            let mut start = 0;
            while let Some(pos) = search_content[start..].find(&query) {
                let absolute_pos = start + pos;
                self.find_matches
                    .push((absolute_pos, absolute_pos + query.len()));
                start = absolute_pos + 1;
            }

            if !self.find_matches.is_empty() {
                if let Some(prev_index) = previous_match_index {
                    if prev_index < self.find_matches.len() {
                        self.current_match_index = Some(prev_index);
                    } else {
                        self.current_match_index = Some(0);
                    }
                } else {
                    self.current_match_index = Some(0);
                }
            }
        }
    }

    pub fn find_next(&mut self, ctx: &egui::Context) {
        if self.find_matches.is_empty() {
            return;
        }

        if let Some(current) = self.current_match_index {
            self.current_match_index = Some((current + 1) % self.find_matches.len());
        } else {
            self.current_match_index = Some(0);
        }

        self.select_current_match(ctx);
        self.should_select_current_match = true;
    }

    pub fn find_previous(&mut self, ctx: &egui::Context) {
        if self.find_matches.is_empty() {
            return;
        }

        if let Some(current) = self.current_match_index {
            self.current_match_index = Some(if current == 0 {
                self.find_matches.len() - 1
            } else {
                current - 1
            });
        } else {
            self.current_match_index = Some(0);
        }

        self.select_current_match(ctx);
        self.should_select_current_match = true;
    }

    pub fn get_current_match_position(&self) -> Option<(usize, usize)> {
        if let Some(index) = self.current_match_index {
            self.find_matches.get(index).copied()
        } else {
            None
        }
    }

    pub fn select_current_match(&self, ctx: &egui::Context) {
        if let Some((start_byte, end_byte)) = self.get_current_match_position() {
            if let Some(active_tab) = self.get_active_tab() {
                let content = &active_tab.content;

                let start_char = content[..start_byte.min(content.len())].chars().count();
                let end_char = content[..end_byte.min(content.len())].chars().count();

                let text_edit_id = egui::Id::new("main_text_editor");
                if let Some(mut state) = egui::TextEdit::load_state(ctx, text_edit_id) {
                    let selection_range = egui::text::CCursorRange::two(
                        egui::text::CCursor::new(start_char),
                        egui::text::CCursor::new(end_char),
                    );
                    state.cursor.set_char_range(Some(selection_range));
                    egui::TextEdit::store_state(ctx, text_edit_id, state);
                }
            }
        }
    }

    pub fn replace_current_match(&mut self, ctx: &egui::Context) {
        if self.find_query.is_empty() || self.find_matches.is_empty() {
            return;
        }

        if let Some((start_byte, end_byte)) = self.get_current_match_position() {
            let replace_query = self.replace_query.clone();
            let replacement_end = start_byte + replace_query.len();

            if let Some(active_tab) = self.get_active_tab_mut() {
                let content = &active_tab.content;

                let mut new_content = content.clone();
                new_content.replace_range(start_byte..end_byte, &replace_query);

                active_tab.content = new_content;
                active_tab.is_modified = true;
            }

            self.update_find_matches();

            if let Some(active_tab) = self.get_active_tab() {
                let replacement_end_char = active_tab.content
                    [..replacement_end.min(active_tab.content.len())]
                    .chars()
                    .count();

                let text_edit_id = egui::Id::new("main_text_editor");
                if let Some(mut state) = egui::TextEdit::load_state(ctx, text_edit_id) {
                    state
                        .cursor
                        .set_char_range(Some(egui::text::CCursorRange::one(
                            egui::text::CCursor::new(replacement_end_char),
                        )));
                    egui::TextEdit::store_state(ctx, text_edit_id, state);
                }
            }
        }
    }

    pub fn replace_all(&mut self, ctx: &egui::Context) {
        if self.find_query.is_empty() || self.find_matches.is_empty() {
            return;
        }

        let find_query = self.find_query.clone();
        let replace_query = self.replace_query.clone();
        let case_sensitive = self.case_sensitive_search;
        let find_matches = self.find_matches.clone();

        if let Some(active_tab) = self.get_active_tab_mut() {
            let content = &active_tab.content;

            let new_content = if case_sensitive {
                content.replace(&find_query, &replace_query)
            } else {
                let mut result = String::new();
                let mut last_end = 0;

                for (start_byte, end_byte) in &find_matches {
                    result.push_str(&content[last_end..*start_byte]);
                    result.push_str(&replace_query);
                    last_end = *end_byte;
                }
                result.push_str(&content[last_end..]);
                result
            };

            active_tab.content = new_content;
            active_tab.is_modified = true;
        }

        self.update_find_matches();

        self.current_match_index = None;

        let text_edit_id = egui::Id::new("main_text_editor");
        if let Some(mut state) = egui::TextEdit::load_state(ctx, text_edit_id) {
            state
                .cursor
                .set_char_range(Some(egui::text::CCursorRange::one(
                    egui::text::CCursor::new(0),
                )));
            egui::TextEdit::store_state(ctx, text_edit_id, state);
        }
    }
}